And yes, I only play draft Dominion. I do managed to pick Kass from time to time by banning correctly. Eg: If enemy team ban Yorick, vs first pick Kass. If they ban Kass, we first pick Yorick. Pick your poison strategy.

if you know how to stay away from trouble or have well-coordinated tanky teammates to protect you, build glass cannon
screw roa, get morello's (or dfg for more burst), deathcap, voidstaff, lichbane, wota

glass cannons ftw

if you want some security, get roa or abyssal for more defensive AP items

Optimally, you want to build him glass canon, but unless you're an epic Kass player or have a solid team, I would refrain from doing so. Some people look down on it, but a Rylai's can be really useful for survivability and the extra slow amount.

However, a glass canon build, or a tank/mana build (for the trolls) is pretty good. Just stack those riftwalks and everything will be k.